Distribution and ecological risk evaluation of bioavailable phosphorus in sediments of El Temsah Lake, Suez Canal

Abstract

Phosphorus reactivity and bioavailability in lake sediments is determined by diverse fractions of phosphorus (P) and their distribution. To gain deeper insights into P dynamics in Lakes, sediments from El Temsah Lake were investigated for water soluble P (WSP), readily desorbable P (RDP), algal available P (AAP) and Olsen-P using different chemical extraction methods. Total P (TP), organic P (OP), inorganic P (IP) contents, were also investigated. The TP, OP and IP concentrations in the sediments were 598.39 µg/g, 199.76 µg/g and 398.63 µg/g, correspondingly. Concentrations of the bioavailable P in the sediments followed the order AAP (48.42 µg/g)>WSP (14.60 µg/g)>RDP (1.82 µg/g)>Olsen-P (1.50 µg/g). Pearson correlation analysis exposed that there were significant correlations among the bioavailable P fractions concentrations and the TP concentrations (r=0.83; p>0.01, r=0.94; p>0.01, r=0.62; p>0.05); for WSP, AAP, and Olsen-P respectively. Moreover, there were no obvious associations amongst total P and N, Al, Ca, Fe, Mg, Mn, and OM in the sediments. The outcomes of phosphorus ecological risk assessment in sediments by single pollution standard index method revealed that the standard index of TP varied from 0.19 to 1.85. It demonstrated that the ecological pollution risks of phosphorus in El Temsah Lake sediments was comparatively low.